Why format code at all?
Formatting changes nothing a computer cares about and everything a person does. A 40 KB API response on one line is technically fine — until you need to find the one field that is null. Consistent indentation shows structure at a glance, turns diffs into real changes instead of whitespace noise, and makes a malformed document fail loudly with a line number instead of quietly further down the pipeline.
Beautify, minify, compare
Beautify for reading and review. Minify for shipping: the JavaScript, CSS and HTML minifiers strip comments and whitespace and rewrite code into shorter equivalents. Compare when something changed and you need to know what — the diff checker marks changed lines and the exact words inside them.
When the code won’t parse
Need something more specific? There are dialect-aware pages for PostgreSQL, MySQL and SQL Server, a JSON compare that ignores key order, and converters such as CSV to JSON and JSON to TypeScript.
Every formatter here has to parse your code first, so it doubles as a syntax checker: errors come with the line, the column and a plain-English reason. On formatter pages, Fix with AI proposes a repaired version for you to review — useful for Python-style dicts pasted as JSON or a query with one missing bracket.
Private by design
The formatting engines — Prettier, sql-formatter, Terser, CSSO and jsdiff — are bundled into the page and run on your device. Your last input on each tool is remembered in this browser so a refresh doesn’t lose work; you can wipe it on the privacy page.